div{
    width: 100px;
    height: 100px;
    border: 1px solid #ccc;
}

@num1:20px;
@num2:@num1+10;
@num3:@num1+@num2;
@num4:(@num1+4)/2;
// @color:#888/2;
@color:#ff0000/2;
@color2:@color+#111;

.d1{
    // font-size: @num2;
    font-size: @num4;
    background: @color2;
    border:(@num1+8)/10 solid blue;
    width: @num1+500;
}